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Winter Model Discussion 12Z 15/1/13 onwards.


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Posted
  • Location: hatfield (herts)
  • Weather Preferences: snow
  • Location: hatfield (herts)

I just posted, in one post, a positive and a negative spin. Essentially, it depends on where you are looking as to how favoured your area will be.

To give an example for where I am from two very short range models - the NAE suggests 5cm up to midday Friday with the main area of snow still to come, the WRF suggests only 1cm by that point and, even by the end of the front giving us less than 5cm because the front decays. The varying totals for your area are very similar for that time frame.

Generally, the met office have issued an amber warning where they are sure of the reach of the snow, it's yellow where it could be disruptive or a non event.

thanks for your reply seems a very confusing time even for the experts.we'll just have to wait and see

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Posted
  • Location: Kilmersdon Radstock Somerset
  • Weather Preferences: None Really but a snow lover deep down
  • Location: Kilmersdon Radstock Somerset

Good evening. Here is tonight's report on the 12z output from the big three namely GFS, UKMO and ECM for tonight Wednesday January 16th 2013.

All models are agreed for the next 48 hours though even at this range the specific detail differs between them. A weak front lies close to West Wales in a cold and slack pool of air over the UK over the next 24 hours. Tomorrow night sees an active frontal system moving into the West of the UK with and area of rain, readily turning to snow inland across Western areas by morning. Through the day the front decelerates as it moves East and the energy gradually slides SE late in the day. Widespread and in places heavy snowfall will occur, heaviest in Central and Western areas away from the far SW. Late in the day as the front slides away and weakens the snow will ease down and die out in most places over Saturday.

GFS then shows a quieter day or so with much of the UK under snow cover with cold conditions prevailing as a weak ridge develops briefly. By Monday further sliding Low pressure over the SW renews the risk of further rain and snowfall before towards midweek the Atlantic breaks through with rain and strong winds developing a rapid thaw of lying snow. The rest of the run shows a changeable pattern with another brief colder incursion through FI while on the whole there would be plenty of wind and rain on a milder wind flow blowing from the West.

The GFS Ensembles show the operational run was one of the milder options tonight though one can't ignore the slow trend to nearer to normal conditions as we move through Week 2. There are plenty of precipitation spikes on offer too indicating that rainfall would be commonplace as the Atlantic Lows push in and over the UK later.

The Jet Flow shows a flow weakly blowing SE over the UK. In a day or two the flow markedly strengthens as it steams across the Atlantic and crosses Europe well to the South of the UK. Eventually the flow ridges over the Atlantic and down over the UK in a week or so time.

UKMO tonight shows Low pressure filling and moving SE over France over the weekend with the legacy of Fridays snow dying out slowly over Saturday. Sunday should be a dry and cold day with a lot of cloud over the snowfields. On Monday a further area of rain and snow moves in from the SW with snow once more disruptive for some although rain is possible in the SW. Through the remaining early days of the week there will be further rain, sleet and snow in places as Low pressure close to the South of Britain fails to make inroads into the cold block over the UK.

ECM tonight shows a very wintry spell indeed with a widespread snow event on Friday subsiding away East and South over the weekend leaving cold and grey conditions for many though in any overnight clear skies some very low temperature values can be expected. By early next week a re-run of Friday seems possible as further Low pressure moves in close to the SW and on down into France by Tuesday. A bitter and strong East wind would develop on this second Low's northern flank with drifting of lying snow a major hazard should this setup verify. Through the middle of the week cold, snowy weather persists especially in the South as Low pressure is slow to move away East to the South of Britain. The end of the run shows the weather finally settling down as High pressure develops over the UK but in very cold air and countrywide snow cover some record breakingly low night time temperatures would be possible.

In Summary tonight the weather looks like staying cold through the reliable part of the output and most likely beyond too. The battleground will continue to be the UK for the next 5-7 days as successive attempts of mild air from the Atlantic try to displace the cold over the UK. The resultant copious snowfall remains a major feature of the weather with some very difficult travelling issues likely over the next week. Longer term various options are shown with GFS taking us on a milder route along with its ensembles while ECM looks like a pattern reload in the closing frame of its operational as the cold block remains to the NE, reaching across to the UK still. With pressure falling to the West the Jet is seen to be travelling South again with more disrupting troughs sliding SE over the UK likely in the days that would follow.

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Posted
  • Location: Broxbourne, Herts
  • Weather Preferences: Snow snow and snow
  • Location: Broxbourne, Herts

This is strange for me. As a cold and snow fan i want the winter to extend and extend (mindful of course that it would cause hardship but also knowing what i wish for does not affect what happens anyway!)

But I'm a GFS fan as well....and while I can understand the criticism it's come in for, I still generally believe it's the best model, if not every three hour shift on every run is measured like it's supposed to be the gospel.

So it's push of the atlantic through the block next week is disappointing....and i have to confess, observing other evidence, unlikely. But i always think its too easy to say "the GFS is always too progressive with the Atlantic" and dismiss it for being so. In fact on the 12z i think it is not as progressive with fridays front as other models are. And I have seen it lead the way with some trends, even in this winter.

So for me, the possibility of a breakthrough next week is unlikely, but not to be dismissed. I hope the GFS is wrong with this, but it will break my heart a little to see it proved so wrong.

Then again....if it right, I don't know if i could bear the heartbreak I'd face over my new-found trust in the CMA :lol:

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Posted
  • Location: Southampton, Hampshire
  • Location: Southampton, Hampshire

Would take a very brave person to call where fronts stall at this juncture. The guys n girls at the MET have no choice, they have to draw the faxes daily but they will be far from confident about it!I have to say though, the faxes are just oozing potential for us though.

Just refering to the Friday event, I suspect the only rain/snow mix will occur literally right on the coast. The rest will be snow. Thereafter it may turn to back to sleet . But that a million miles away in snow forecasting terms yet.

The difference perhaps for us as opposed to others living more inland and more to the NE is that a decent snowfall is nearly nailed for them, they have an insurance policy, we don't, if it trends east it will be predominately rain here.

But what I like so much about what I'm seeing here is that, whilst there will be winners and losers, I can only see more potential snow events on the horizon. So miss out on one, cop for the next hopefully. That'll do me!

Quite agree S4. One other factor to consider is the actual strength of the front itself so it's possible the precipitation could fizzle out quite a lot the further E it gets. I'm in the same boat geographically as yourself so I am not pinning too much hope on Friday's system but yes, there sure looks like more of the same in the coming days.

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Posted
  • Location: Afan Valley South 4 Miles Port Talbot
  • Location: Afan Valley South 4 Miles Port Talbot

Quite agree S4. One other factor to consider is the actual strength of the front itself so it's possible the precipitation could fizzle out quite a lot the further E it gets. I'm in the same boat geographically as yourself so I am not pinning too much hope on Friday's system but yes, there sure looks like more of the same in the coming days.

From what I can gather from Fax chart, and forecasts on here friday looks a rain event for me in South Wales (Swansea ish) but its been a rollercaster ride last few weeks thats for sure.

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Posted
  • Location: Central London near Canary Wharf
  • Location: Central London near Canary Wharf

Then again....if it right, I don't know if i could bear the heartbreak I'd face over my new-found trust in the CMA laugh.png

Believe mate believebiggrin.png

CMA T120 Holding the cold in

cmanh-1-120.png

Edited by ChartViewer
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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

Quite agree S4. One other factor to consider is the actual strength of the front itself so it's possible the precipitation could fizzle out quite a lot the further E it gets. I'm in the same boat geographically as yourself so I am not pinning too much hope on Friday's system but yes, there sure looks like more of the same in the coming days.

I also think that snow showers will become a much bigger feature for the north and east as winds strengthen and pressure falls, it won't just be the main frontal zone(s) that have all the snow, so for places like n and ne scotland where friday continues to look dry but cold, your snowfest should arrive by friday night and onwards well into next week, n.ireland and western scotland, infact ireland in general should also be turning much colder too with a risk of snow replacing the current rain and drizzle.

Edited by Frosty039
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Posted
  • Location: West Dorset
  • Weather Preferences: Warm summers, Snowy winters.
  • Location: West Dorset

This is strange for me. As a cold and snow fan i want the winter to extend and extend (mindful of course that it would cause hardship but also knowing what i wish for does not affect what happens anyway!)

But I'm a GFS fan as well....and while I can understand the criticism it's come in for, I still generally believe it's the best model, if not every three hour shift on every run is measured like it's supposed to be the gospel.

So it's push of the atlantic through the block next week is disappointing....and i have to confess, observing other evidence, unlikely. But i always think its too easy to say "the GFS is always too progressive with the Atlantic" and dismiss it for being so. In fact on the 12z i think it is not as progressive with fridays front as other models are. And I have seen it lead the way with some trends, even in this winter.

So for me, the possibility of a breakthrough next week is unlikely, but not to be dismissed. I hope the GFS is wrong with this, but it will break my heart a little to see it proved so wrong.

Then again....if it right, I don't know if i could bear the heartbreak I'd face over my new-found trust in the CMA laugh.png

Yet again the GFS precipitation chart stands up to the NAE and I am with you somewhat with the GFS.

gfs-2-54.png?12

13011812_1612.gif

It is poor when it fails to deliver what you want and a god when it does. Personally I think it is consistent and that is not just about the precipitation output.

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Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

New thread coming soon guys.

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Posted
  • Location: Gilesgate Moor, Durham City
  • Location: Gilesgate Moor, Durham City

I also think that snow showers will become a much bigger feature for the north and east as winds strengthen and pressure falls, it won't just be the main frontal zone(s) that have all the snow, so for places like n and ne scotland where friday continues to look dry but cold, your snowfest should arrive by friday night and onwards well into next week, n.ireland and western scotland, infact ireland in general should also be turning much colder too with a risk of snow replacing the current rain and drizzle.

Here in NE England my sense is that the potential for significant convection has largely been missed because of the focus on the frontal system.

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Posted
  • Location: Rochester, Kent.
  • Location: Rochester, Kent.

Yet again the GFS precipitation chart stands up to the NAE and I am with you somewhat with the GFS.

gfs-2-54.png?12

13011812_1612.gif

It is poor when it fails to deliver what you want and a god when it does. Personally I think it is consistent and that is not just about the precipitation output.

The NAE is only out to 6am Friday morning. The frontal system won't have reached most eastern areas by then.

Edited by manutdmatt1986
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Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

New thread here

Closing this one now.

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